Following common practice [1]}, [2]}, [3]}, [4]}, we adopt mean intersection over union (mIoU) and foreground-background IoU (FB-IoU) as our evaluation metric. The mIoU averages over all IoU values for all object classes such that \(\mathrm {mIoU} = \frac{1}{C}\sum _{c=1}^{C} \mathrm {IoU}_{c}\) , where \(C\)  is the number of classes in each fold, e.g., \(C = 20\)  for COCO-20\(^{i}\) . FB-IoU disregards the object classes and averages over foreground and background IoU, \(\mathrm {IoU}_\mathrm {F}\)  and \(\mathrm {IoU}_\mathrm {B}\) , such that \(\mathrm {FBIoU} = \frac{1}{2}(\mathrm {IoU}_\mathrm {F} + \mathrm {IoU}_\mathrm {B})\) . As stated in [1]}, we mainly focus on mIoU since it better accounts for generalization power of a model than FB-IoU.
